An existing system provides an electrical feedback to compensate for aging by the drive transistors and by the organic light emitting devices (OLEDs) in the pixels of a display panel. The display panel can broken into several blocks. In each frame, the electrical aging of a very small number of pixels can be measured by each block. Thus, a full-panel scan is a very lengthy process, causing problems in the presence of fast-aging phenomena and thermal effects.
For example, assuming a panel size of 600×800 pixels or 1200×1600 sub-pixels, if a control circuit controls 210 columns, eight of such circuits are needed. Suppose the frame rate is 60 Hz, and 10 sub-pixels in each of the eight circuits are measured in each frame simultaneously, a full-panel scan period is: 1200*210/10/60/60 or 7 minutes. As a result, the compensation of an aged/relaxed area with an absolute value difference of 100 from the initial estimation, takes at least 100*7=700 minutes or over 11 hours, an unacceptably excessive amount of time. A more efficient compensation scheme is needed.